Expansible arbors



March 20, 1956 H. c. SPAHN 2,738,980

EXPANSIBLE ARBORS Filed March 20, 1955 INVENTOR/ MW ATTORNEYS various kinds and similar machines.

, Patented Mar. 2o,- 1956 U i ed States Hilbert a le, Ira-mac, Ill.

, I Application March 20,1isf 'se'riti1Ne. 343,570

5. nds (Cl'. -27:9- '--2).. i

easily mounted and rigidly secured while being machined,

as well as readily removed after being completed, to pro vide a' form offarhorwhich can be made in various sizes to'meet the requirements o different johs and which an 'arbor maybe expanded 'or eont racted for us with bores having a given range of ditferent sizes 'l accomplish these obje'ctsfby 'th erneans shown in the accompanying drawings,i n which" "Figure 1 is'a side quarter-sectional lev'ation" of my arbor; i

Figure 2 is an end View of theouter endf lingersid l tormed thereonwhich are engaged by the shoulderring in the but Theseret iners thus ]-a t to restrict the expansion of 'p InQ rder to drive the fxpansion b rs inwardly along the sloping section s 9 and thus expand them, driving bars 7 ar s1ida 1y mountedgupon,thethreaded portion ofthe banll with their innenendsresting upon a reduced circumferential ring ofi the bar .betweenthe expansionbars andthefnuflora washer 11 which maybe interposed between the outer endsof thedriving bars and the nut;

all tim s.

' ,Figure 3 is a cross-section on the line 3--'3 of Figured; I v

Figure 4 is a detail of one of the sliding barsg Figure 5 is a sectional view of a bar on the line 5 5 of Figure 4 Similar numerals refer to similar parts throughout the several views. r U

My arbor includes asolid round bar 1" of steel or 'other suitable metal taperedslightly froni the shank end to v the middle and may be flattened at one 'end 2"to fit the toolholderof the lathe and prevent rotation ofthe arbor bar'. H. t At the middle of the arbor bar 'I'prov'ide an enlarged flatring '10which. may be integral with the bar or f'o'rmed separately and united thereto by a pressfit or by w'elding or other suitable means.

The opposite end of the bar is reduced in diameter and has threads 3 to receive'a' nut' li' *'A portion ofjthe nut is cut with an internal shoulder 6L1? The parf'of the bar between the ring 10 and the threads 3 is tapered and provided with a plurality of radial channels 5 preferably eight. Between the channels or grooves 5 the projecting sections 9 of the shaft or bar 1 have their outer angular faces flattened as shown in the drawings and tapered longitudinally to correspond with the taper of the shaft or bar 1.

Upon the angular faces of these intermediate sections 9 expansion bars 8 are mounted with their outer surfaces corresponding approximately to arcs of the inner circumference of the ring 10. These bars are formed with inwardly projecting ribs or splines 8.1 which extend a short distance into the channels 5.

Within the channels 5 retainer rods 6 are mounted having lugs or fingers 6.2 at the inner ends thereof which seat in notches formed in the inner ends of the bars. The outer ends of the retainers have similar lugs or @When the; nut isftightened or screwed fupv upon its threads, the driving bar willexert pressure upon the expansion barsj to driv" em inwardly along the sloping sections [thereby expe ngsaidbars. In theoperationo f this arbor the nut 4,is

sloping sectigns, thereby reducing; the diameter of the periphery. thereofienoug'hto permit the bore of the piece to be machinedto be mounted by passing over the nut and placed. lip on the arbor. "The nut is then tightened and the expansionbars forced into contact with the inner circumference of the .bore -whereby the piece i will be readily ,held against sli 'aping either lonigtudinally or cir- I cumferentially.

.IILorder to retain [the expansion'bars and the driving bars in, their places, {circumferential grooves 12-12 are form dftlie'rein andcoiledvsprings 12.1. are mounted in thejgr ovesftouexert, pressure inwardly upon'the bars at ,My arborrmay' be. arranged tot-hold different sized p eces vor parts to, be operated on'by the lathe, eithe'r by increasing; the dimensions of all the parts or byYinc're'a'singfthegthickuess of the .part B as-shown in Figilre'fS. I1." l i v I e lth aththe threads 3 are formed upon T It will 1 b the reduced' right ehdjofthe bar orshaft 1 and'cooperate with similar. ,h reads }formed upon: the inner circumference of the nut}. ."N'o threadsare formed upon the retainer Qstrips .6,I butthey'lare free to. slide either 'inlor outfa' controlledjby l thelugslor fingers which contact the-annular shoulder; 6.1 at the outer ends thereof orthe lugs or fingers 6 2 at. the inner endsof the retainer strips v6. When the}: t'd isgscrewed nwardly upon the threads 3, the' WaSher 11 is. foreed"againsttheouter end of the driving'bars'l and: they in 'turndrive the expansion bars 8 along-the upwardslopeof the bar ,or shaft 1 and are thereby expandedv against a workpiece mounted thereon. "The, iter ends of t he'retainer rods or strips 6" are reduced in jsize so as -,to clear the threads 3 of the nut:

-= 4andallw the nut and expansion bars of plates to move longitud' 'a'u r the barorshaftzl, except as restrained r g' s. .y ang n -sh lder.6,1 t

various ehang es' may be made in "he "sizes, dimensions and proportions'of the parts without departing from the spirit of my invention as expressed in the claims and I do not limit my claim to the precise forms shown in the drawings.

I claim:

1. The combination in an arbor for metal lathes, of a longitudinal central bar tapered from an enlarged circular midsection of the bar and having one end adapted to fit the chuck of a lathe and its free end reduced in diameter and fitted with spiral threads, a plurality of longitudinal channels extending from the enlarged portion to and through the threaded end of the central bar between and in alternation with the channels and sloping inwardly from the midsection to the threaded end, each rib having a pair of fiat laterally inclined faces at its outer edge, a corresponding plurality of expansion bars each slidably mounted upon the nearest lateral faces of two the bars, when the nut is'lunscrewed or moved outwardly V e r e I turned out- 'wardly to carrythe'expansion bars outwardly along the successive ribs, and adapted to expand as they are driven toward the enlarged midsection to afforda firm grip upon-- an annular workpiece mounted upon the arbor, an adjustable nut mounted upon the threaded end of the cen- 'tral bar=arranged to operate a plnrali'tybf driuin'gjbars corresponding in number to" tl'lieiki'oansioflbizi'sifihd mounted upon the ribs adjacent the hilt having their inner ends' bearing against the adjacent 'end of the expansion bars and their outerends incont'ac'tiviththe'nuflwhe y the expansion bars will bediiir'en inwaidly along tne ribs when the ntit i's' tu'rned inwardly upon'the threads and may move outwardly when thelnutis retracted, the

sets of expansion bars and dri iiigbarshaying interwardly when advanced and: to draw the retainer strips mediate circumferential grooves formed therein j, "th coiled tension-springs seatedin the grooves adapted t'o'it; tain the bars frorn'di'splacement. l j j 2. In anarbor for nietal'lathes including a'long'i t'u'dinal central bar tapered from anenlarged circular tnidsection of the bar and having oneend rjeduce'd in diameter and fitted with spiral threads, "a plurality of longitudinal channels extending from the enlarged portion to and through the threaded end of thefcentralbarbetween and in alternation with, the channels'and sloping inwardly 4 y from the midsection to the threaded end, each rib having a pair, of fiat laterally inclined faces at its outer edge, a corresponding plurality of expansion bars each slidably mounted upon the nearest lateral faces of two successive ribs, and adapted to expand as they are driven toward the enlargedmidsection to afford a firm grip upon an annular workpiece mounted upon the arbor, an adjustable nut mounted upon the threadedend of the central bar arranged to operate a plurality of driving bars corresponding in number to the expansion bars and mounted upon the ribs adjacent the nut'with' their inner ,endsbearing against the adjacent ends of the ex'pansion bars and their outer ends in contact with the nut whereby theexpan's ion bars will be driven inwardly alongthe ribs 'whenthe nut is turned inwardly upon the threads" and may move outwardly when the nut is retracted, the expansion bars having longitudinal splines thereon pr ojectinginto their respective channels, and being movable outwardly by retainer strips mounted in the charinels,.each having a I responding intermediate upstanding ribs integral with th central-barbetweenthe channels, each rib having two fiat lateral faces extending the full length thereof at its outer edge to afford a supportfor expansion bars and for driving bars all mounted upon the ribs with inward longitudinal splines extending into and slidable in their respective channels, each expansion bar and each driving bar being slidable upon '*'thenearest lateral faces of two successive ribs, retainer, strips slidably mounted in the channels attached'al't 'their' ends to the inner ends of the expansion bars and:with their outer ends engaged by a nut adjustably mountedupon the threaded end of the central ar'b'o'r bar adapted to actuate the driving bars inoutwardly when retracted.

4. An arbor as described in claim 3, the sets of expansion bars and driving bars having circumferential grooves cut therein with coiled tension springs seated in the gr'oo es to retain them from displacement.

5. An arbor for metal lathes including a central longitudinalaft'ierbar adapted to be held in a chuck with its free'end tapered and having a reduced spirally threaded outer i'ejrid, a plurality of uniform longitudinal channels extending" along'the tapered part of the bar and the threaded end 'thereofifliipstanding intermediate sections of the ibanbetw'ee'n the adjacent channels and sloping to the thr eadedpo'rtion of thebar each intermediate sectit'm havingi'tivo lateral outer faces flattened and standing at' an a gle to" each other, a plurality of expansion bars each slidably mounted on the lateral faces of the two upstanding sections adjacent thereto, the outer faces of are 'expansien'ba'r's being formed on arcs similar to the eireumterence of a circle, a nut mounted upon the threaded end of the ar erear; driving liars mounted upon the upstanding sectioiis near he' threaded end of the arbor bar'with their inneiends bearing against the outer ends of the expansion bars-respectively and their outer ends 1 adaptedtdb contactedand ir'ioved inwardly by rotation of the nut, the sets of expansion bars and driving bars finger upon its inner end in engagerhent with' the inner 1 with the outer reduced portion spirally threaded, a pin rality of uniform fiat-bottomed channels with parallel sides extending along the tapered part of the bar and'to and through the threaded end portion thereof corhaving circumferential g'r'ooycs formed therein with re- 'siliiit nieans' seated therein toretain them from disp a emen j j p References Cited in the file of this patent "UNiT'ED' STATES PATENTS. ,122,920; "Simons; Jan. 23, 1872 189,483, 1 1877 291,282; 1 1884 447,667 1891 714,448 1902 1,588,787 1926 1,902,176 1933 2,392,259" Palotsee Jan. 1, 1946 FOREIGN PATENTS 40,670, s t 'srlarld, Dec. 6, 1907 1927 451,389, Germany V........' Oct. 21, 

